A damper device is disposed on, for example, a path of motive power transmission between an engine and a speed-change transmission, in order to absorb (or suppress) torque fluctuations caused by the engine and the speed-change transmission. Among others there is a damper device including a damper unit that absorbs the torque fluctuations under a spring force, a hysteresis unit that absorbs (or suppresses) the torque fluctuations by the hysteresis torque caused by friction or the like, and a limiter unit that produces slip when torsion of a rotational shaft can no longer be absorbed by the damper unit or the hysteresis unit. In a motive power transmission system, having such damper device, chattering noise caused by gears in the speed-change transmission is produced due to engine vibrations. In particular, if, in a motive power transmission device loaded on a hybrid vehicle provided with an engine and an electric motor as motive power sources, an input shaft of the speed-change transmission is coupled via a planetary gear mechanism to the electric motor, which may also be a motor-generator, severe gear chattering may be produced in the speed-change transmission as a result of engine vibrations. To suppress such gear chattering from occurring, there is known a damper device of the type in which an inertial body is connected to the damper device on the motive power transmission path between the engine and the motive power transmission.
Patent Literature 1, for example, discloses a damper for a hybrid driving apparatus in which torque fluctuations produced by first and second power supply sources are suppressed in transmitting the torque. The damper includes a first rotational member driven in rotation by the first power supply source, and a second rotational member coupled to the second power supply source via a planetary gear mechanism. The damper also includes a torsion member that suppresses torque fluctuations between the first and second rotational members and a limiter mechanism that interrupts the transmission of the motive power from the first rotational member to the second rotational member when the torque fluctuations between the first and second rotational members have reached a pre-set value. The damper further includes an inertial body provided on the first rotational member or on the second rotational member. In FIG. 7 of Patent Literature 1, the second rotational member is coupled to a carrier shaft of the planetary gear mechanism. The inertial body has its inner rim part coupled by splined engagement to the carrier shaft, so that the inertial body is non-rotatable relative to the carrier shaft while being displaceable in the axial direction. Elastic member(s) of rubber or synthetic resin is provided in an axial gap formed between the inertial body and the second rotational member and in an axial gap formed between the inertial body and the carrier shaft.    Patent literature 1: JP Patent Kokai JP-A-2002-13547 (FIG. 7)